THE WONDERS OF LIFE 



selection, for the theory of descent which Lamarck had 

 proposed fifty years before. 



In sliarp contrast to this purely empirical method, 

 which is favored by most men of science in our day, we 

 have the purely speculative tendency which is current 

 among our academic philosophers. The great regard 

 which the critical philosophy of Immanuel Kant obtained 

 during the nineteenth century has recently been in- 

 creased in the various schools of philosophy. As is 

 known, Kant affirmed that only a part of our knowl- 

 edge is empirical, or a posteriori — that is, derived from 

 experience; and that the rest of our knowledge (as, for 

 instance, mathematical axioms) is a priori — that is to 

 say, reached by the deductions of pure reason, inde- 

 pendently of experience. This error led to the further 

 statement that the foundations of science are meta- 

 physical, and that, though man can attain a certain 

 knowledge of phenomena by the innate forms of space 

 and time, he cannot grasp the "thing in itself" that lies 

 behind them. The purely speculative metaphysics 

 which was built up on Kant's apriorism, and which 

 found its extreme representative in Hegel, came at 

 length to reject the empirical method altogether, and 

 insisted that all knowledge is obtained by pure reason, 

 independently of experience 

 I Kant's chief error, which proved so injurious to the 



I whole of subsequent philosophy, lay in the absence of 

 I any physiological and phylogenetic base to his theory 

 of knowledge; this was only provided sixty years after 

 his death by Darwin's reform of the science of evolution, 

 ^ and by the discoveries of cerebral physiologists. He 

 ^ regarded the human mind, with its innate quality of 

 reason, as a completely formed entity from the first, and 

 I made no inquiry into its historical development. Hence, 

 " he defended its immortality as a practical postulate, 

 incapable of proof; he had no suspicion of the evolution 



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